A superalloy target wherein the superalloy target has a polycrystalline structure of random grain orientation, the average grain size in the structure is smaller than 20 m, and the porosity in the structure is smaller than 10%. Furthermore, the invention includes a method of producing a superalloy target by powder metallurgical production, wherein the powder-metallurgical production starts from alloyed powder(s) of a superalloy and includes the step of spark plasma sintering (SPS) of the alloyed powder(s).

A sliding member includes a base material and an amorphous hard carbon film formed on a surface of the base material, and the amorphous hard carbon film has a graded structure in which a sp.sup.2 ratio increases from an inner surface side corresponding to the base material side toward an outer surface side. A piston ring includes the sliding member.

A thermal barrier coating includes a highly porous layer and a dense layer. The highly porous layer is formed on a heat-resistant base, is made of ceramic, has pores, has a layer thickness of equal to or larger than 0.3 mm and equal to or smaller than 1.0 mm, and has a pore ratio of equal to or higher than 1 vol % and equal to or lower than 30 vol %. The dense layer is formed on the highly porous layer, is made of ceramic, has a pore ratio of equal to or lower than 0.9 vol % that is equal to or lower than the pore ratio of the highly porous layer, and has a layer thickness of equal to or smaller than 0.05 mm.

A method of manufacturing a ferroelectric element includes forming an insulating film on one side of a metal substrate by an electron beam (EB) vapor deposition method or a sputtering method; forming a metal film on the insulating film by the sputtering method; and forming a ferroelectric film on the metal film by a sol-gel method. The metal substrate includes iron (Fe) and nickel (Ni), and a content of the nickel (Ni) is greater than or equal to 30% and less than or equal to 40%.

A friction material comprises an Fe part which contains Fe as a main component, a coating layer formed on a surface of the Fe part, and a friction part formed on a surface of at least a part of the coating layer, and the coating layer comprises a first coating layer and a second coating layer which have a specific average thickness and a specific component in order from Fe part side, and in the second coating layer, in order of positions at which the thickness is 20%, 40%, 60% and 80% of the second coating layer from the side of the first coating layer to the side opposite thereto, a Cu content increases and a Ni content decreases.

A sliding member includes a base material, and an amorphous hard carbon film formed on a surface of the base material, in which a sp.sup.2 ratio of the amorphous hard carbon film increases from an inner surface side corresponding to the base material side toward an outer surface side thereof to become a maximum value and further decreases toward the outer surface side.

The radiation-selective absorber coating, in particular for an absorber tube of a parabolic trough collector, includes a reflective layer which is reflective in the infrared range, at least one barrier layer arranged below the reflective layer, at least one absorption layer arranged above the reflective layer, an antireflection layer arranged above the absorption layer and at least one adhesion-enhancing layer arranged between the barrier layer and the reflective layer. The adhesion-enhancing layer preferably is a molybdenum layer, but can also be provided by a copper, titanium, titanium oxide, or silicon layer. The adhesion-enhancing layer preferably has a thickness of 5 to 50 nm.

A sliding member includes a base material and an amorphous hard carbon film formed on a surface of the base material, and the amorphous hard carbon film has a graded structure in which a sp.sup.2 ratio increases from an inner surface side corresponding to the base material side toward an outer surface side. A piston ring includes the sliding member.

An article includes a substrate, a bond coat layer disposed on the substrate, and a layer of networked ceramic nanofibers disposed on the bond coat layer.

In an intermediate layer formed between a base material and a DLC layer, a Ti layer and a TiC layer formed on a surface of the Ti layer are provided, and a carbon content of the entire layer containing the Ti layer and the TiC layer is 53 at % or more and 77 at % or less.